<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div class=""><br class=""></div>Although “unique” was too strong a claim, I’m still looking into what drives my sense of the DMR C compiler being special for its time.<div class=""><br class=""></div><div class="">The “Advent of Computing” podcast has an interesting episode on Bliss this month:</div><div class=""><a href="https://open.spotify.com/episode/6q3XuPkcTPEa5GTP5i8EZb" class="">https://open.spotify.com/episode/6q3XuPkcTPEa5GTP5i8EZb</a></div><div class="">It (deliberately) doesn’t mention C all that much, but gives a nice view of another “systems language” of the early 70’s. Note that the podcast does not focus on the optimising aspect of the Bliss compiler; in my view this was an important aspect of both the Wulff and DMR compilers.</div><div class=""><br class=""></div><div class="">For those interested in the topic, my work on the BCPL -> B -> Eh -> Zed lineage is steadily progressing: based on the surviving papers and theses I’ve reconstructed most of the Eh compiler:</div><div class=""><a href="https://gitlab.com/pnru/Thoth" class="">https://gitlab.com/pnru/Thoth</a></div><div class="">As it stands it can compile Eh source to TI990 machine code, but the reconstruction is not finished (for example the library code is mostly missing). I hope to find time to finish this project in the next months.</div><div class=""><br class=""></div><div class="">Doing a compare and contrast of BCPL, B, Bliss, C, Eh and Zed gives a nice context around the choices that DMR discusses in his paper on the development of early C. Note however that Eh/Zed is a journey: the Eh of 1975 was almost identical to the B that Johnson took there and it evolved from there. The quality of the compiler improved significantly in 1976/77. The evolution to a soft typed language (i.e. Zed) was the final step and only occurred around 1978/79.</div><div class=""><br class=""></div><div class="">I remain interested in any bits of Toth source code that might have survived, as well as in contacting members of the Uni of Waterloo / Mike Malcolm portable computing project.</div><div class=""><br class=""><div><br class=""><blockquote type="cite" class=""><div class="">Begin forwarded message:</div><br class="Apple-interchange-newline"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(0, 0, 0, 1.0);" class=""><b class="">From: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class="">Paul Ruizendaal <<a href="mailto:pnr@planet.nl" class="">pnr@planet.nl</a>><br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(0, 0, 0, 1.0);" class=""><b class="">Subject: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class=""><b class="">Re: [TUHS] On the uniqueness of DMR's C compiler</b><br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(0, 0, 0, 1.0);" class=""><b class="">Date: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class="">31 May 2024 at 14:00:55 CEST<br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(0, 0, 0, 1.0);" class=""><b class="">To: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class="">"<a href="mailto:tuhs@tuhs.org" class="">tuhs@tuhs.org</a>" <<a href="mailto:tuhs@tuhs.org" class="">tuhs@tuhs.org</a>><br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(0, 0, 0, 1.0);" class=""><b class="">Cc: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class="">Clem Cole <<a href="mailto:clemc@ccc.com" class="">clemc@ccc.com</a>><br class=""></span></div><br class=""><div class=""><meta http-equiv="Content-Type" content="text/html; charset=utf-8" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">I’m further looking into BCPL / B / C family compilers on 16-bit mini-computers prior to 1979.<div class=""><br class=""></div><div class="">Lot’s of interesting stuff. BCPL was extended with structures at least twice and plenty struggle with (un)scaled pointers. It seems that the Nova was a much easier target than the PDP-11, with a simpler code generator sufficing to generate quality code. I’ll report more fully when I’m further along with my review.</div><div class=""><br class=""><div class=""><blockquote type="cite" class=""><div class="">On May 8, 2024, at 5:51 PM, Clem Cole <<a href="mailto:clemc@ccc.com" class="">clemc@ccc.com</a>> wrote:</div><div class=""><div dir="ltr" class=""><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br class=""></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">IIRC, Mike Malcom and the team built a true B compiler so they could develop Thoth. As the 11/40 was one of the original Thoth target systems, I would have expected that to exist, but I have never used it.</div></div></div></blockquote><br class=""></div><div class="">Yes, they did. I’m working through the various papers on Thoth and the Eh / Zed compilers (essentially B with tweaks). I’ve requested pdf’s of two theses that are only on micro-fiche from the Uni of Waterloo library, hopefully this is possible. The original target machines were Honeywell 6060, DG Nova, Microdata 1600/30 and TI-990. The latter is close enough to a PDP-11. This compiler is from 1976.</div><div class=""><br class=""></div><div class="">I’ve browsed around for surviving Thoth source code, but it would seem to be lost. Does anyone know of surviving Thoth bits?</div><br class=""><div class=""><br class=""></div></div></div></div></blockquote></div><br class=""></div></body></html>